Australia has failed to hold a closing press conference at the G20 leaders' summit even though it is taking over the presidency of the group for 2014.

Other leaders addressed the world's media at the end of the two-day summit in St Petersburg, but foreign minister Bob Carr initially delayed and then cancelled his appearance.

Puzzled foreign journalists were left to ask Australian reporters whether Carr would be talking at any point.

A spokesman for the minister later justified the decision not to hold an official media briefing by stating: "Australia is represented in the joint statement issued at the end of the conference."

Australia was criticised earlier in the week for sending Carr to Russia instead of prime minister Kevin Rudd, who has been campaigning in the federal election.

Australia takes charge of the G20 from December, and is currently the president of the UN security council.

On Friday Carr denied Australia had been too quick to back a US-led strike against Syria as Barack Obama struggled to persuade other world leaders to support punitive military action in response to the Assad regime's alleged use of chemical weapons.

"The position we adopted was correct," the foreign minister said before the second working meeting.

"If the world doesn't respond in a way that's appropriate and proportionate, then other dictators will think they can gas children."

Australia was among the 11 countries that supported a "strong international response to the attack.

"We support efforts undertaken by the US and other countries to reinforce the prohibition on the use of chemical weapons," the countries said.

Only France has vowed to actually join an American intervention.

Most EU nations, along with emerging powers Brazil and India, and others, are reticent about resorting to military action without a mandate from the UN.